Solve all terraform/terragrunt warnings

[marcoieni]

We use a few deprecated resources or attributes. This might be a good opportunity to also install a tool like tflint to follow best practices.

We could also adopt security static analyzers like:

• https://github.com/aquasecurity/trivy
• https://www.checkov.io/

Context

This issue was originally part of #437

[ubiratansoares]

It worths mentioning that tflint has some plugins with additional rules/checks we could make the most of :

• https://github.com/terraform-linters/tflint-ruleset-aws
• https://github.com/terraform-linters/tflint-ruleset-google

There is also a Github Action available to ease running tflint within our CI.